Uplink time synchronization in a communication system

1. A method for uplink time synchronization in a communication system, the method comprising the steps of: receiving uplink data from a user equipment; storing a time error of the uplink data along with a time stamp; integrating the time error in an accumulator to provide an accumulated time error; dumping the accumulated time error upon the time stamps of the accumulated data meeting a timing condition; comparing the accumulated time error against a threshold; and scheduling a time advance with the user equipment if the accumulated time error exceeds the threshold.

2. The method of claim 1 , wherein the accumulated time error is: y M = ∑ n = 1 M ⁢ { x ⁡ ( n ) + W ⁡ ( n ) ⁢ F ⁡ ( x ⁡ ( n ) , x ⁡ ( k - 1 ) ) } where x(n) is the time error of sample n, k is a last valid sample, M is a total number of accumulated samples, W is a weighting function, and F is a filling function for missing data.

3. The method of claim 1 , wherein the integrating step includes removing invalid data using a weighting function.

4. The method of claim 3 , wherein the weighting function is W ⁡ ( n ) = { 0 ; if ⁢ ⁢ x ⁡ ( n ) ⁢ ⁢ has ⁢ ⁢ a ⁢ ⁢ bad ⁢ ⁢ C ⁢ ⁢ R ⁢ ⁢ C 0 ; if ⁢ ⁢ x ⁡ ( n ) ⁢ ⁢ is ⁢ ⁢ not ⁢ ⁢ scheduled n - k ; otherwise } where x(n) is input sampled data, n is a last sample, and k is a last valid sample.

5. The method of claim 1 , wherein the integrating step includes filling in missing data.

6. The method of claim 5 , wherein the filing function for missing data is F ⁢ { x ⁡ ( n ) , x ⁡ ( k + 1 ) } = { [ x ⁡ ( n ) + x ⁡ ( k - 1 ) ] / 2 ; when ⁢ ⁢ 1 ≤ ( n - k ) ≤ T sp ( n - k - 1 ) ⁢ x ⁡ ( n ) ; when ⁢ ⁢ ( n - k ) > T sp x ⁡ ( n ) ; otherwise } where x(n) is input sampled data, n is a last sample, k is a last valid sample, and Tsp is a maximum time window.

7. The method of claim 1 , wherein the comparing step includes normalizing the accumulated time error by a number of samples.

8. The method of claim 1 , wherein the threshold (Th) of the comparing step is chosen for different given UE configurations as: Th = { 1 / M ; M ⁢ ⁢ U - M ⁢ ⁢ I ⁢ ⁢ M ⁢ ⁢ O 2 / M ; S ⁢ ⁢ U - M ⁢ ⁢ I ⁢ ⁢ M ⁢ ⁢ O ⁢ ⁢ Rank ⁢ ⁢ 2 1 / M ; S ⁢ ⁢ U - M ⁢ ⁢ I ⁢ ⁢ M ⁢ ⁢ O ⁢ ⁢ Rank ⁢ ⁢ 1 1 / M ; S ⁢ ⁢ I ⁢ ⁢ M ⁢ ⁢ O } where M is a number of accumulated samples.

9. The method of claim 1 , wherein in the dumping step, the timing condition is a length of the time stamps of the accumulated data exceeding a maximum time window.

10. The method of claim 9 , wherein the accumulated time error is set to a number of uplink data samples times a time error of a last sample.

11. The method of claim 1 , wherein in the dumping step, the timing condition is a length of the time stamps of the accumulated data exceeding a minimum time window.

12. An eNodeB operable for uplink synchronization of mobile stations in a communication system, the eNodeB comprising: a transceiver operable to receive user equipment uplink data transmissions; and a processor coupled to the transceiver, the processor operable to store a time error of the uplink data along with a time stamp, integrate the time error in an accumulator to provide an accumulated time error, dump the accumulated time error upon the time stamps of the accumulated data meeting a timing condition, comparing the accumulated time error against a threshold, and scheduling a time advance to be sent by the transceiver to the user equipment if the accumulated time error exceeds the threshold.